234 SUMMARY OF CURRENT RESEARCHES RELATING TO 



The mean of several analyses of vasculose gives the following 

 composition, C 59-3; H 5*5; 35-2 per cent. ; corresponding to the 

 formula G^JImOi^. It contains, therefore, more carbon, less hydi-ogen 

 and oxygen than cellulose. 



Cutose is, in its chemical properties, the most interesting of all 

 the substances which make up the skeleton of plants ; in its properties 

 and composition it approaches fatty bodies, but diifers from them in 

 certain well-defined characters. It constitutes a portion of the epi- 

 dermis of leaves. Maceration of leaves for a month in water at 30°- 

 35° C. enables the vascular bundles on the one hand and the epidermal 

 membrane on the other to be separated mechanically ; a few minutes 

 immersion in boiling hydrochloric acid answers the same purpose. 

 The epidermis thus obtained is composed of three different substances ; 

 on the surface is a resinous substance soluble in boiling alcohol ; 

 underneath are two other membranes closely adherent to one another, 

 but possessed of different properties ; the innermost is composed of a 

 cellulose-substance insoluble in the ammoniacal copper reagent except 

 after the action of boiling hydrochloric acid, consisting principally of 

 paracellulose ; the outer of these two layers consists of a special 

 substance, cutose. 



The leaves of Agave furnish a convenient source of cutose, which 

 can be obtained pure in the following manner. The crude cutose- 

 membrane is first treated with boiling alcohol, which dissolves the 

 resin always present on the surface of leaves ; the fatty substances are 

 then removecl by ether, and the cellulose-substances are eliminated 

 by trihydrated sulphuric acid ; vasculose appears never to occur in 

 the epidermis. Pure cutose, thus obtained, resists the action of strong 

 reagents, such as trihydi-ated sulphuric acid, hydrochloric acid, 

 ammonia, and cold dilute solutions of potassa and soda ; but oxidizing 

 agents and boiling alkaline solutions jiroduce in it interesting modifi- 

 cations. Nitric acid produces first of all resinous substances, and 

 finally suberic acid. Dilute boiling solutions of alkalies and even of 

 alkaline carbonates dissolve cutose and change it into a kind of soap 

 which is soluble in water, but insoluble both in excess of alkali and 

 in alkaline salts such as sodiiun chloride. The same effect is pro- 

 duced by baryta, strontia, and lime. Two new fatty acids are formed 

 by the action of bases, one solid, the other liquid, which the authors 

 propose to call stearocutic and oleocutic acids. The latter resombles 

 in its character other liquid fatty acids ; but the former presents some 

 peculiar properties. It is white, fusible at 76° C, nearly insoluble 

 in cold alcohol and ether, and dissolves with difficulty in boiling 

 alcohol ; its best solvents are benzine and crystallizable acetic acid, 

 crystallizing from them in small needles ; when once fused it yields 

 on cooling a resinous substance which is no longer crystallizable. Its 

 combinations with alkalies have special properties which are described 

 in detail. The two acids combine with one another under the influence 

 of boiling alcohol, producing a double acid. Attempts to produce 

 the alcohol of the series of either acid have at i^resent entirely failed. 

 It would appear that these two acids are actually present in cutose in 

 an isomeric condition which can be induced by a high temperature, 



